Concave side of proximal thoracic zone vulnerable to pedicle screw perforation in adolescent idiopathic scoliosis surgery: Comparative analysis of pre- and intraoperative computed tomography navigation

Concave side of proximal thoracic zone vulnerable to pedicle screw perforation in adolescent idiopathic scoliosis surgery: Comparative analysis of pre- and intraoperative computed tomography navigation | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Concave side of proximal thoracic zone vulnerable to pedicle screw perforation in adolescent idiopathic scoliosis surgery: Comparative analysis of pre- and intraoperative computed tomography navigation Tomohiro Yamada, Yamato Yu, Tomohiko Hasegawa, Go Yoshida, Tomohiro Banno, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5452062/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Purpose To evaluate the accuracy of pedicle screw (PS) and clarify the characteristics of pre- or intraoperative perforation using computed tomography (CT) navigation in adolescent idiopathic scoliosis (AIS) surgery. Methods One hundred and seven patients who underwent surgery were retrospectively selected. Overall, 853 PSs were implanted in 48 patients using preoperative CT, whereas 1,059 PSs were implanted in 59 patients using intraoperative CT with a second intraoperative 3-dimensional (3D) scan. We analyzed the postoperative CT images for pedicle perforation using Rampersaud criteria. Results Total PS placement accuracy (grade A, B) was significantly higher in the intraoperative group than the preoperative CT group (97.2% vs 94.8%, respectively; P = 0.008). Accuracy was significantly higher among Lenke type 1 AIS cases in the intraoperative CT group (97.8% vs 95.1%, respectively; P = 0.014). Grade D perforation occurred most frequently at the concave side of proximal thoracic (PT) zone, followed by the transitional PT/main thoracic zone in both groups. The second intraoperative 3D scan allowed the re-insertion of 10 screws to prevent grade D perforation in the intraoperative CT group. Conclusions Both navigation systems were sufficiently accurate. However, surgeons must be careful at the concave side of the PT zone. Intraoperative CT navigation yielded higher accuracy by using the intraoperative second 3D scan than preoperative navigation. pedicle screw computed tomography navigation adolescent idiopathic scoliosis proximal thoracic Figures Figure 1 Figure 2 Introduction Pedicle screws (PSs) comprise the most prevalent segmental fixation system to stabilize all three columns of the spine in adolescent idiopathic scoliosis (AIS) surgery. After Suk et al. provided their initial results of thoracic PS placement [ 20 ], PSs provide stable anchor points connected to rods, which can aid the surgical management of complex spinal deformities in AIS. However, PS perforation has the potential risk of correction loss, neurological deficits, and organ damage [10; 12]. The incidence of abnormal pedicles in AIS was as high as 31.9% [ 19 ], and they often exist at the concavity of the PT zone [19; 25]. The visceral structures at risk during PS insertion in a scoliosis patient differ at each vertebral level. There is also a higher risk of injury to the spinal cord at the PT concave side screws at the T2 and T3 levels and main concave sides at the T5–T9 levels [ 9 ]. To improve insertion accuracy, several reports revealed that various assistive methods, including intra- and preoperative computed tomography (CT) navigation, enable improved PS placement accuracy compared with the conventional freehand technique [4; 13; 21]. Zhang et al. recently reported that intraoperative navigation systems facilitated PS insertion in the apical region compared with preoperative CT-based navigation [ 27 ]. Intraoperative CT navigation features good and bad aspects. First, surgeons do not require spine registration, which can cause errors in preoperative CT navigation [ 3 ]. Besides, the surgeon could use a second three-dimensional (3D) scan to confirm screw position. In contrast, longer surgeries requiring multiple X-rays increase patient radiation exposure [ 2 ]. However, few studies have clarified the advantage of intraoperative CT navigation, including the second 3D scan, compared with preoperative CT navigation in AIS surgery. We believe that determining the effectiveness of intraoperative CT navigation will allow surgeons to optimize the use of intraoperative CT navigation. Therefore, this study aimed to compare the PS accuracy and perforation characteristics between pre- and intraoperative CT navigation in AIS surgery. Moreover, it aimed to identify the specific zone where the PS perforation rate increased in both groups. Finally, it aimed to demonstrate the usefulness of the second intraoperative 3D CT scan that contributed to the improved accuracy rates. Materials and Methods This retrospective radiological study was based on a prospective patient database from a single academic spinal surgery department. Between 2013 and 2022, we conducted a retrospective review of patients with AIS who underwent corrective fusion surgery (T2–L5) via pedicular segmental instrumentation using intra- or preoperative CT navigation. The intraoperative spinal 3D imaging system was developed using an O-arm (Medtronic Navigation, Louisville, CO, USA). We regularly performed AIS surgery using intra- or preoperative CT navigation. To compare screw accuracy under the strictest conditions, we compared PS accuracy using intra- or preoperative CT from same-day surgery based on Lenke AIS [ 15 ] and zone classification [ 1 ]. To maximize accuracy, axial scans as well as sagittal and coronal reconstructions were reviewed. This study was approved by our local institutional review board (#20–189), which waived the requirement for informed consent because of the retrospective nature of the research. Surgical technique All surgeries were performed under general anesthesia with the patient in the prone position on an Allen table. Preoperative prone CT scans were used to identify the anatomic variation resulting from the rotation, angulation, and translation of each vertebral segment as well as the extent of spinal canal abnormalities. Routine scans were performed to assess the thin pedicle, whereas extensive CT scan cuts were used for stereotactic guidance. When cancellous bone was lacking in the pedicle on the preoperative CT scan, we canceled the PS placement. During surgery, a reference frame was fixed to the spine close to the vertebrae to be instrumented [ 5 ]. In the preoperative CT navigation group, registration was performed at each of the three vertebrae from the caudal side. In the intraoperative CT group, each scan was performed to cover as many vertebrae as possible from the most caudal vertebra within the reference frame. To determine the PS insertion points, the facets were identified after careful exposure of the involved spinal segments and the localizing pedicle probe was placed at the base of the superior articular facet as well as the midpoint of the transverse process and the pars interarticularis. While referencing the point bar, we chose the insertion point and trajectory. During the intraoperative navigation surgery, we performed the second 3D scan to evaluate the screw direction; if unacceptable, we re-inserted it. Radiological evaluation Rampersaud criteria were used to evaluate the screw position and direction of screw breach using a postoperative axial CT scan [ 14 ]. According to these criteria, patients were categorized into four grades: A, entirely in the pedicle; B, 4 mm breach. Oversized screws touching the medial and lateral cortices were considered part of grade A unless the breach was > 2 mm. Based on the fact that screws perforating the canal for up to 2 mm were considered acceptable [7; 16], grades A and B were categorized as accurate. We also evaluated intraoperative re-insertion cases in the intraoperative CT group. Operative time and blood loss were compared between groups, while radiation dosage using the dose-length product (DLP) calculation was determined in the intraoperative CT group. Statistical analysis Descriptive statistics are depicted as mean and standard deviation and were calculated for demographic data and radiographic parameters. Differences in individual and radiographic parameters were assessed using an unpaired t- test, the chi-squared test, and Fisher’s exact test. All statistical computations were performed using Statistical Package for the Social Sciences software (version 26.0; IBM Corp., Armonk, NY, USA). Values of p < 0.05 were considered statistically significant. Results A total of 1,948 PSs (107 patients) were analyzed. Patient age, sex proposition, Lenke classification, and preoperative major Cobb angle did not differ significantly between groups (Table 1 ). The screw accuracy rates were 97.2% in the intraoperative CT group, significantly higher than in the preoperative CT group (94.8%). Table 2 shows the perforation rates (grade C or D) based on Lenke classification. The perforation rate was the highest among Lenke type 2 AIS cases of the preoperative CT group (7.1%) as well as Lenke type 3 AIS cases of the intraoperative CT group (11.3%). The perforation rate among Lenke type 1 AIS cases was significantly higher in the preoperative (5.2%) versus intraoperative CT group (2.3%) ( P = 0.014). Table 1 Patient demographic, curve classification and Cobb angle. Preoperative CT Intraoperative CT N 48 59 P Age (years) 14.8 ± 1.8 14.2 ± 1.8 0.100 Female (%) 43 (86) 53 (89.8) 0.967 Total number of screws 853 1095 Lenke classification 1 26 (54.2) 29 (49.2) 0.194 2 7 (14.6) 13 (22.0) 3 0 (0) 3 (5.1) 5 11 (22.9) 11 (18.6) 6 4 (8.3) 3 (5.1) Major Cobb angle (°) 47.4 ± 5.5 49.5 ± 7.6 0.082 Table 2 Number of screws inserted and perforation rate stratified by curve classification. Preoperative CT Intraoperative CT Type Screw (%) Perforation (%) Screw (%) Perforation (%) P 1 464 (54.4) 24 (5.2) 532 (48.5) 12 (2.3) 0.014* 2 154 (18.1) 11 (7.1) 276 (25.2) 10 (3.6) 0.105 3 - - 53 (4.8) 6 (11.3) - 5 146 (17.1) 6 (4.1) 167 (15.2) 3 (1.8) 0.222 6 89 (10.4) 3 (3.4) 67 (6.1) 0 (0) 0.129 853 44 (5.2) 1095 31 (2.8) 0.0081* *significantly difference. Table 3 shows the grade D perforation distribution according to zone classification in both groups. Grade D perforation occurred much more often in the preoperative group versus the intraoperative group in the concave proximal thoracic (PT) and transitional main thoracic/lumbar (MT/L) zones. Overall, there were 18 perforations in the preoperative CT group versus 13 perforations in the intraoperative CT group. In the intraoperative CT group, the second 3D scan enabled re-insertion of the perforated screw. Screw re-insertion decreased the number of grade D perforations from 13 to 4. Grade D perforations occurred much more often in the preoperative group versus the intraoperative CT group in the concave PT and transitional MT/L zones. Table 4 shows the grading shift in the perforated screw before and after the second 3D scan in the intraoperative CT group. A total of 10 PSs were re-inserted after the confirmational scan, leading to screw salvage. The mean operative time was significantly higher in the intraoperative than preoperative CT group ( P = 0.033). However, there was no intergroup difference in estimated blood loss. The mean DLP in the intraoperative group was 365 mGy-cm. Table 3 Zone distribution of the grade D perforation in preoperative and intraoperative group. Preoperative CT Intraoperative CT* Intraoperative CT† Zone medial lateral medial lateral medial lateral Concave PT 3 5 1 3 0 1 Convex PT 2 0 0 2 0 0 Transitional PT/MT 1 0 1 1 0 1 Concave MT 0 1 0 2 0 0 Transitional MT/L 0 4 1 1 0 0 Concave L 0 2 0 1 0 1 Total 6 12 3 10 0 3 Intraoperative CT * ; Before performing second 3-dimensional scan. Intraoperative CT † ; After performing second 3-dimensional scan. Table 4 Perforation grading before and after second 3-dimensional scan in the intraoperative CT group. Type Zone Before After 1 Concave PT C A 1 Concave PT D skip 1 Concave PT D B 2 Convex PT D B 2 Convex PT D B 2 Transitional PT/MT C A 2 Transitional MT/L C A 5 Transitional MT/L D B 5 Concave MT D A 6 Concave MT D skip Representative case 1 A 14-year-old girl presenting with Lenke type 2A AIS and a major Cobb angle of 56° at T7–L1 underwent corrective fusion surgery at T2–L2 using preoperative CT navigation. Postoperative neurological testing revealed no deterioration; however, the postoperative CT showed a medial grade D perforation at the right T6 at the concave side of the PT zone (Fig. 1 ). The patient required re-insertion surgery. Representative case 2 A 14-year-old girl presenting with Lenke type 5C AIS and a major Cobb angle of 47° at T10–L3 underwent corrective fusion surgery at T6–L3 using intraoperative CT navigation. A second intraoperative 3D scan indicated a medial grade D perforation at the left T9 pedicle and transitional MT/L zone. The second 3D scan enabled screw re-insertion, correcting the perforation to grade A (Fig. 2 ). Discussion The present study aimed to investigate PS insertion accuracy and perforation characteristics with the use of preoperative versus intraoperative CT navigation. Our results revealed that the accuracy of intraoperative CT navigation (97.2%) was significantly higher than that of intraoperative CT navigation (94.8%). Perforation was more than twice as likely to occur among Lenke type 1 AIS cases in the preoperative CT group. Our results also demonstrated that screw perforation was more likely to occur at the concave side of PT to the MT/L transition, in which cases the use of intraoperative 3D CT navigation facilitated screw re-insertion. A previous study found no significant difference in total screw accuracy for intraoperative versus preoperative CT [ 27 ]. However, that study did not re-evaluate screw position with a second intraoperative 3D scan to minimize radiation exposure. On the contrary, screw re-insertion during a second intraoperative 3D scan increased the placement accuracy rate [ 24 ]. In this respect, the present study reflected the importance of re-evaluating inserted screws using a second 3D scan in the intraoperative CT group. Indeed, without the second intraoperative 3D scan, the number of the grade D perforations would have been almost identical between groups. Our result suggested that use of the O-arm surely contributed to increased accuracy of AIS surgery (Table 4 ). Furthermore, the present study also precisely compared the two groups. Use of the second intraoperative 3D scan resulted in extra radiation exposure in the intraoperative group (Table 5 ). With the second intraoperative 3D CT, the DLP was 365 ± 172 mGy-cm, an acceptable value considering national diagnostic reference levels in Japan [ 18 ]. Therefore, use of the O-arm including the second intraoperative 3D scan would be acceptable because it is consistent with the principle of medical radiation exposure benefits outweighing risks [ 8 ]. Table 5 Comparison for operative time and absorbed radiation in both groups. Preoperative CT Intraoperative CT 48 59 P Operative time (min) 236 ± 48 255 ± 45 0.033* EBL (ml) 364 ± 267 453 ± 409 0.100 DLP (mGy-cm) - 365 ± 172 EBL: Estimated blood loss, DLP; Dose length product. *significantly difference. From the literature, several factors concerning the concave side of PT are vulnerable to PS perforation. An analysis of thoracic pedicle width using normal specimens demonstrated minimal width in the T3–T5 region, especially in the T4 right pedicle [ 17 ]. However, when determining range of fixation in AIS among Lenke type 1 and 2 AIS cases, the area around T2–T4 is subjected to upper instrumented vertebra [ 23 ]. The pedicle on the concave side of the PT curve in AIS has morphological characteristics that make it riskier for PS insertion as well as a small diameter at the isthmus [ 6 ]. Distance from the reference frame is associated with PS perforation. Oba et al. analyzed the PS perforation in AIS surgery using O-arm navigation [ 11 ]. They clarified that perforation occurred in 2.7% of cases, and that the perforation rate by the ninth or subsequent screws was significantly higher than for the previous screws. Chan et al. revealed that the highest rate of lateral perforation was at the concave side of the PT zone using the freehand or fluoroscopic technique [ 1 ]. At the proximal site, screw insertion maneuver may be influenced by an inadequate skin incision site. Similar to these studies, we demonstrated that lateral perforation occurred most frequently at the concave side of the PT zone in both groups (Table 3 ). We also demonstrated that the confirmational intraoperative CT enabled re-insertion of the perforated screw, thereby increasing placement accuracy compared with preoperative CT navigation (Table 4 ). These results highlight the need to pay attention to the area at the concave side of the PT zone when using preoperative or intraoperative CT navigation. Notably, screw perforation occurred more frequently in the transitional PT/MT or transitional MT/L zone than at the apical vertebra, such as the concave MT, convex MT, concave L, or convex L zones, which involved the greatest degree of rotation (Table 4 ). On the contrary, Zhang et al. compared intraoperative and preoperative navigation techniques [ 27 ], pointing out that the apical vertebrae were most vulnerable to perforation due to being the most rotated. A possible explanation for this might be that surgeons would be more influenced by the change in trajectory at the transitional versus apical vertebrae [ 26 ]. This study has some limitations. First, screw misplacement possibly occurred during the correction maneuvers. Even if accurate screw insertion is achieved, correction forces, such as distraction, compression, and rod rotation force, can induce PS perforation in fragile bony cases [ 22 ]. Second, in the intraoperative CT group, we could not detect the exact number of the re-inserted screws because the surgeon decided whether to perform the second 3D scan. Therefore, if the second 3D scan was performed in all cases, a higher accuracy rate would have been noted in the intraoperative group. Despite these limitations, the present study results provide useful information regarding the characteristics of PS perforation using pre- versus intraoperative CT navigation in AIS surgery. In conclusion, PS insertion using pre- or intraoperative CT navigation in AIS surgery was accurate, reliable, and safe. The use of O-arm navigation allowed the surgeon to re-insert misplaced screws and increased the placement accuracy rate. The analysis of screw perforation in these cases highlighted the need to pay attention to the concave PT zone in Lenke type 1 or 2 AIS cases. Declarations Funding: There was no funding source for the work that resulted in the article or the preparation of the article Author Contribution Tomohiro Yamada wrote and prepared the manuscript, and all of the authors participated in the study design. All authors have read, reviewed, and approved the article. Acknowledgement We would like to thank Editage (www.editage.jp) for English language editing. Data Availability Raw data were generated at Hamamatsu University School of Medicine. Derived data supporting the findings of this study are available from the corresponding author on request. References Andrade C (2018) Sedative Hypnotics and the Risk of Falls and Fractures in the Elderly. 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Arch Orthop Trauma Surg 143(4):1861–1867 Zhang W, Takigawa T, Wu Y, Sugimoto Y, Tanaka M, Ozaki T (2017) Accuracy of pedicle screw insertion in posterior scoliosis surgery: a comparison between intraoperative navigation and preoperative navigation techniques. Eur Spine J 26(6):1756–1764 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5452062","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":381868001,"identity":"5f582a2f-7c4a-4ea6-803e-632e7c64dd1f","order_by":0,"name":"Tomohiro Yamada","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA0ElEQVRIiWNgGAWjYJACiQQGCzn74w1ApoEF0VokjBnOHABpkSBSCxAlNtxIgLIJAf723oc3HtRIMDbOfH51w48CCaBIdwJ+G84cN7ZIOCbBzCydU3azB+gwiTNnN+DVYiCRxiaRwCbBxiadk3aDB6jFQCKXGC3/JHh4JM+k3fxDtJbENgkgYD92myhbJM4cY7ZI7JMwMODJYbstYyDBQ9Av/O1tjDd/fLOp38B+/NnNN39s5IBhiF8LEuAxAJPEKgcB9gekqB4Fo2AUjIIRBABGWUD3gGfh/AAAAABJRU5ErkJggg==","orcid":"","institution":"","correspondingAuthor":true,"prefix":"","firstName":"Tomohiro","middleName":"","lastName":"Yamada","suffix":""},{"id":381868002,"identity":"b6dd7e7a-44ec-44e4-8ffd-a091babf6c75","order_by":1,"name":"Yamato Yu","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Yamato","middleName":"","lastName":"Yu","suffix":""},{"id":381868005,"identity":"cad8acff-d7d7-4217-bbb6-45df3f894f57","order_by":2,"name":"Tomohiko Hasegawa","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Tomohiko","middleName":"","lastName":"Hasegawa","suffix":""},{"id":381868012,"identity":"be845b41-46f8-40a0-bd61-90a0fd67397e","order_by":3,"name":"Go Yoshida","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Go","middleName":"","lastName":"Yoshida","suffix":""},{"id":381868014,"identity":"3cede621-63c8-4c45-8761-005cce3b05ce","order_by":4,"name":"Tomohiro Banno","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Tomohiro","middleName":"","lastName":"Banno","suffix":""},{"id":381868017,"identity":"e7f3a9b8-84ed-4835-b126-6feb094681cf","order_by":5,"name":"Hideyuki Arima","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Hideyuki","middleName":"","lastName":"Arima","suffix":""},{"id":381868022,"identity":"18adc7b6-b20b-4d81-96a4-904fb800be6d","order_by":6,"name":"Shin Oe","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Shin","middleName":"","lastName":"Oe","suffix":""},{"id":381868025,"identity":"4f2a7d5f-3034-41de-a2f2-19ffb25f127f","order_by":7,"name":"Koichiro Ide","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Koichiro","middleName":"","lastName":"Ide","suffix":""},{"id":381868027,"identity":"29a2bfd4-6e4a-4139-9c59-8d4265f71f50","order_by":8,"name":"Kenta Kurosu","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Kenta","middleName":"","lastName":"Kurosu","suffix":""},{"id":381868029,"identity":"3c6fe725-6b07-4baa-b678-755badd62d77","order_by":9,"name":"Yukihiro Matsuyama","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Yukihiro","middleName":"","lastName":"Matsuyama","suffix":""}],"badges":[],"createdAt":"2024-11-14 08:08:22","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5452062/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5452062/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":71890173,"identity":"0a20d433-f60a-4b2c-979e-8edd978cf76c","added_by":"auto","created_at":"2024-12-19 12:55:15","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":102518,"visible":true,"origin":"","legend":"\u003cp\u003eA 14-year-old girl presented with Lenke type 2A adolescent idiopathic scoliosis and a major Cobb angle of 56° at T8–L1 underwent corrective fusion surgery of T2–L2 using preoperative CT navigation\u003c/p\u003e\n\u003cp\u003e(A, B) Pre- and postoperative whole spine radiographs. The white arrow indicates the right T6 pedicle. (C) Postoperative CT scan showing a grade D medial perforation at the left T6 pedicle.\u003c/p\u003e","description":"","filename":"figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5452062/v1/5416b8ae3cd86e82f7645234.jpg"},{"id":71890175,"identity":"6d6e8ef1-d124-4f2b-89c2-9ba48dbe5c9c","added_by":"auto","created_at":"2024-12-19 12:55:16","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":98995,"visible":true,"origin":"","legend":"\u003cp\u003eA 14-year-old girl presented with Lenke type 5C adolescent idiopathic scoliosis and a major Cobb angle of 47° at T10–L3 underwent corrective fusion surgery at T6–L3 using intraoperative computed tomography (CT) navigation\u003c/p\u003e\n\u003cp\u003e(A) Preoperative whole spine radiograph. The white arrow indicates the left T9 pedicle.\u003c/p\u003e\n\u003cp\u003e(B) Intraoperative second 3D scan showing a medial grade D perforation at the left T9 pedicle. We then re-inserted the screw.\u003c/p\u003e\n\u003cp\u003e(C) Postoperative whole spine radiograph. The white arrow head indicates the left T9 pedicle.\u003c/p\u003e\n\u003cp\u003e(D) Postoperative CT scan showing a grade A perforation at the left T9 pedicle.\u003c/p\u003e","description":"","filename":"figure2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5452062/v1/a91eef38816334ce10d16b27.jpg"},{"id":71890197,"identity":"1d0a68ff-bf02-4c9d-951c-108fa107302f","added_by":"auto","created_at":"2024-12-19 12:55:28","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":710676,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5452062/v1/e2d18579-c869-4890-aa58-b6ee9c8c7c6d.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Concave side of proximal thoracic zone vulnerable to pedicle screw perforation in adolescent idiopathic scoliosis surgery: Comparative analysis of pre- and intraoperative computed tomography navigation","fulltext":[{"header":"Introduction","content":"\u003cp\u003ePedicle screws (PSs) comprise the most prevalent segmental fixation system to stabilize all three columns of the spine in adolescent idiopathic scoliosis (AIS) surgery. After Suk et al. provided their initial results of thoracic PS placement [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e], PSs provide stable anchor points connected to rods, which can aid the surgical management of complex spinal deformities in AIS. However, PS perforation has the potential risk of correction loss, neurological deficits, and organ damage [10; 12]. The incidence of abnormal pedicles in AIS was as high as 31.9% [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], and they often exist at the concavity of the PT zone [19; 25]. The visceral structures at risk during PS insertion in a scoliosis patient differ at each vertebral level. There is also a higher risk of injury to the spinal cord at the PT concave side screws at the T2 and T3 levels and main concave sides at the T5\u0026ndash;T9 levels [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eTo improve insertion accuracy, several reports revealed that various assistive methods, including intra- and preoperative computed tomography (CT) navigation, enable improved PS placement accuracy compared with the conventional freehand technique [4; 13; 21]. Zhang et al. recently reported that intraoperative navigation systems facilitated PS insertion in the apical region compared with preoperative CT-based navigation [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Intraoperative CT navigation features good and bad aspects. First, surgeons do not require spine registration, which can cause errors in preoperative CT navigation [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Besides, the surgeon could use a second three-dimensional (3D) scan to confirm screw position. In contrast, longer surgeries requiring multiple X-rays increase patient radiation exposure [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eHowever, few studies have clarified the advantage of intraoperative CT navigation, including the second 3D scan, compared with preoperative CT navigation in AIS surgery. We believe that determining the effectiveness of intraoperative CT navigation will allow surgeons to optimize the use of intraoperative CT navigation. Therefore, this study aimed to compare the PS accuracy and perforation characteristics between pre- and intraoperative CT navigation in AIS surgery. Moreover, it aimed to identify the specific zone where the PS perforation rate increased in both groups. Finally, it aimed to demonstrate the usefulness of the second intraoperative 3D CT scan that contributed to the improved accuracy rates.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003eThis retrospective radiological study was based on a prospective patient database from a single academic spinal surgery department. Between 2013 and 2022, we conducted a retrospective review of patients with AIS who underwent corrective fusion surgery (T2\u0026ndash;L5) via pedicular segmental instrumentation using intra- or preoperative CT navigation. The intraoperative spinal 3D imaging system was developed using an O-arm (Medtronic Navigation, Louisville, CO, USA). We regularly performed AIS surgery using intra- or preoperative CT navigation. To compare screw accuracy under the strictest conditions, we compared PS accuracy using intra- or preoperative CT from same-day surgery based on Lenke AIS [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] and zone classification [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. To maximize accuracy, axial scans as well as sagittal and coronal reconstructions were reviewed. This study was approved by our local institutional review board (#20\u0026ndash;189), which waived the requirement for informed consent because of the retrospective nature of the research.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eSurgical technique\u003c/h2\u003e \u003cp\u003eAll surgeries were performed under general anesthesia with the patient in the prone position on an Allen table. Preoperative prone CT scans were used to identify the anatomic variation resulting from the rotation, angulation, and translation of each vertebral segment as well as the extent of spinal canal abnormalities. Routine scans were performed to assess the thin pedicle, whereas extensive CT scan cuts were used for stereotactic guidance. When cancellous bone was lacking in the pedicle on the preoperative CT scan, we canceled the PS placement. During surgery, a reference frame was fixed to the spine close to the vertebrae to be instrumented [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. In the preoperative CT navigation group, registration was performed at each of the three vertebrae from the caudal side. In the intraoperative CT group, each scan was performed to cover as many vertebrae as possible from the most caudal vertebra within the reference frame.\u003c/p\u003e \u003cp\u003eTo determine the PS insertion points, the facets were identified after careful exposure of the involved spinal segments and the localizing pedicle probe was placed at the base of the superior articular facet as well as the midpoint of the transverse process and the pars interarticularis. While referencing the point bar, we chose the insertion point and trajectory. During the intraoperative navigation surgery, we performed the second 3D scan to evaluate the screw direction; if unacceptable, we re-inserted it.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eRadiological evaluation\u003c/h3\u003e\n\u003cp\u003eRampersaud criteria were used to evaluate the screw position and direction of screw breach using a postoperative axial CT scan [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. According to these criteria, patients were categorized into four grades: A, entirely in the pedicle; B, \u0026lt;\u0026thinsp;2 mm breach; C, 2\u0026ndash;4 mm breach; and D, \u0026gt;\u0026thinsp;4 mm breach. Oversized screws touching the medial and lateral cortices were considered part of grade A unless the breach was \u0026gt;\u0026thinsp;2 mm. Based on the fact that screws perforating the canal for up to 2 mm were considered acceptable [7; 16], grades A and B were categorized as accurate.\u003c/p\u003e \u003cp\u003eWe also evaluated intraoperative re-insertion cases in the intraoperative CT group. Operative time and blood loss were compared between groups, while radiation dosage using the dose-length product (DLP) calculation was determined in the intraoperative CT group.\u003c/p\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eDescriptive statistics are depicted as mean and standard deviation and were calculated for demographic data and radiographic parameters. Differences in individual and radiographic parameters were assessed using an unpaired \u003cem\u003et-\u003c/em\u003etest, the chi-squared test, and Fisher\u0026rsquo;s exact test. All statistical computations were performed using Statistical Package for the Social Sciences software (version 26.0; IBM Corp., Armonk, NY, USA). Values of \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05 were considered statistically significant.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 1,948 PSs (107 patients) were analyzed. Patient age, sex proposition, Lenke classification, and preoperative major Cobb angle did not differ significantly between groups (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The screw accuracy rates were 97.2% in the intraoperative CT group, significantly higher than in the preoperative CT group (94.8%). Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows the perforation rates (grade C or D) based on Lenke classification. The perforation rate was the highest among Lenke type 2 AIS cases of the preoperative CT group (7.1%) as well as Lenke type 3 AIS cases of the intraoperative CT group (11.3%). The perforation rate among Lenke type 1 AIS cases was significantly higher in the preoperative (5.2%) versus intraoperative CT group (2.3%) (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.014).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePatient demographic, curve classification and Cobb angle.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePreoperative CT\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eIntraoperative CT\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eN\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (years)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e14.2\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemale (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e43 (86)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e53 (89.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.967\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal number of screws\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e853\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1095\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLenke classification\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e26 (54.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e29 (49.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003e0.194\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7 (14.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e13 (22.0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0 (0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3 (5.1)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11 (22.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11 (18.6)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4 (8.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3 (5.1)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMajor Cobb angle (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e47.4\u0026thinsp;\u0026plusmn;\u0026thinsp;5.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e49.5\u0026thinsp;\u0026plusmn;\u0026thinsp;7.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.082\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eNumber of screws inserted and perforation rate stratified by curve classification.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"8\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003ePreoperative CT\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003eIntraoperative CT\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eType\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eScrew (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePerforation (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eScrew (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003ePerforation (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e464 (54.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e24 (5.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e532 (48.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e12 (2.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.014*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e154 (18.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11 (7.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e276 (25.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e10 (3.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.105\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e53 (4.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e6 (11.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e146 (17.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6 (4.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e167 (15.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e3 (1.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.222\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e89 (10.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3 (3.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e67 (6.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e0 (0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.129\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e853\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e44 (5.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1095\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e31 (2.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.0081*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"8\"\u003e*significantly difference.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e shows the grade D perforation distribution according to zone classification in both groups. Grade D perforation occurred much more often in the preoperative group versus the intraoperative group in the concave proximal thoracic (PT) and transitional main thoracic/lumbar (MT/L) zones. Overall, there were 18 perforations in the preoperative CT group versus 13 perforations in the intraoperative CT group. In the intraoperative CT group, the second 3D scan enabled re-insertion of the perforated screw. Screw re-insertion decreased the number of grade D perforations from 13 to 4. Grade D perforations occurred much more often in the preoperative group versus the intraoperative CT group in the concave PT and transitional MT/L zones. Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e shows the grading shift in the perforated screw before and after the second 3D scan in the intraoperative CT group. A total of 10 PSs were re-inserted after the confirmational scan, leading to screw salvage. The mean operative time was significantly higher in the intraoperative than preoperative CT group (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.033). However, there was no intergroup difference in estimated blood loss. The mean DLP in the intraoperative group was 365 mGy-cm.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eZone distribution of the grade D perforation in preoperative and intraoperative group.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"10\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003ePreoperative CT\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003eIntraoperative CT*\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e \u003cp\u003eIntraoperative CT\u0026dagger;\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eZone\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003emedial\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003elateral\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003emedial\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003elateral\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003emedial\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003elateral\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eConcave PT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eConvex PT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTransitional PT/MT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eConcave MT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTransitional MT/L\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eConcave L\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"10\" nameend=\"c10\" namest=\"c1\"\u003e \u003cp\u003eIntraoperative CT\u003cb\u003e*\u003c/b\u003e; Before performing second 3-dimensional scan.\u003c/p\u003e \u003cp\u003eIntraoperative CT\u003cb\u003e\u0026dagger;\u003c/b\u003e; After performing second 3-dimensional scan.\u003c/p\u003e\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePerforation grading before and after second 3-dimensional scan in the intraoperative CT group.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eType\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eZone\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBefore\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAfter\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eConcave PT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eA\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eConcave PT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eskip\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eConcave PT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eB\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eConvex PT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eB\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eConvex PT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eB\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTransitional PT/MT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eA\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTransitional MT/L\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eA\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTransitional MT/L\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eB\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eConcave MT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eA\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eConcave MT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eskip\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e\n\u003ch3\u003eRepresentative case 1\u003c/h3\u003e\n\u003cp\u003eA 14-year-old girl presenting with Lenke type 2A AIS and a major Cobb angle of 56\u0026deg; at T7\u0026ndash;L1 underwent corrective fusion surgery at T2\u0026ndash;L2 using preoperative CT navigation. Postoperative neurological testing revealed no deterioration; however, the postoperative CT showed a medial grade D perforation at the right T6 at the concave side of the PT zone (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The patient required re-insertion surgery.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eRepresentative case 2\u003c/h2\u003e \u003cp\u003eA 14-year-old girl presenting with Lenke type 5C AIS and a major Cobb angle of 47\u0026deg; at T10\u0026ndash;L3 underwent corrective fusion surgery at T6\u0026ndash;L3 using intraoperative CT navigation. A second intraoperative 3D scan indicated a medial grade D perforation at the left T9 pedicle and transitional MT/L zone. The second 3D scan enabled screw re-insertion, correcting the perforation to grade A (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe present study aimed to investigate PS insertion accuracy and perforation characteristics with the use of preoperative versus intraoperative CT navigation. Our results revealed that the accuracy of intraoperative CT navigation (97.2%) was significantly higher than that of intraoperative CT navigation (94.8%). Perforation was more than twice as likely to occur among Lenke type 1 AIS cases in the preoperative CT group. Our results also demonstrated that screw perforation was more likely to occur at the concave side of PT to the MT/L transition, in which cases the use of intraoperative 3D CT navigation facilitated screw re-insertion.\u003c/p\u003e \u003cp\u003eA previous study found no significant difference in total screw accuracy for intraoperative versus preoperative CT [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. However, that study did not re-evaluate screw position with a second intraoperative 3D scan to minimize radiation exposure. On the contrary, screw re-insertion during a second intraoperative 3D scan increased the placement accuracy rate [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. In this respect, the present study reflected the importance of re-evaluating inserted screws using a second 3D scan in the intraoperative CT group. Indeed, without the second intraoperative 3D scan, the number of the grade D perforations would have been almost identical between groups. Our result suggested that use of the O-arm surely contributed to increased accuracy of AIS surgery (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Furthermore, the present study also precisely compared the two groups. Use of the second intraoperative 3D scan resulted in extra radiation exposure in the intraoperative group (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). With the second intraoperative 3D CT, the DLP was 365\u0026thinsp;\u0026plusmn;\u0026thinsp;172 mGy-cm, an acceptable value considering national diagnostic reference levels in Japan [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Therefore, use of the O-arm including the second intraoperative 3D scan would be acceptable because it is consistent with the principle of medical radiation exposure benefits outweighing risks [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison for operative time and absorbed radiation in both groups.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePreoperative CT\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eIntraoperative CT\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOperative time (min)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e236\u0026thinsp;\u0026plusmn;\u0026thinsp;48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e255\u0026thinsp;\u0026plusmn;\u0026thinsp;45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.033*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEBL (ml)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e364\u0026thinsp;\u0026plusmn;\u0026thinsp;267\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e453\u0026thinsp;\u0026plusmn;\u0026thinsp;409\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDLP (mGy-cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e365\u0026thinsp;\u0026plusmn;\u0026thinsp;172\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003eEBL: Estimated blood loss, DLP; Dose length product.\u003c/p\u003e \u003cp\u003e*significantly difference.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eFrom the literature, several factors concerning the concave side of PT are vulnerable to PS perforation. An analysis of thoracic pedicle width using normal specimens demonstrated minimal width in the T3\u0026ndash;T5 region, especially in the T4 right pedicle [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. However, when determining range of fixation in AIS among Lenke type 1 and 2 AIS cases, the area around T2\u0026ndash;T4 is subjected to upper instrumented vertebra [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. The pedicle on the concave side of the PT curve in AIS has morphological characteristics that make it riskier for PS insertion as well as a small diameter at the isthmus [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Distance from the reference frame is associated with PS perforation. Oba et al. analyzed the PS perforation in AIS surgery using O-arm navigation [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. They clarified that perforation occurred in 2.7% of cases, and that the perforation rate by the ninth or subsequent screws was significantly higher than for the previous screws. Chan et al. revealed that the highest rate of lateral perforation was at the concave side of the PT zone using the freehand or fluoroscopic technique [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. At the proximal site, screw insertion maneuver may be influenced by an inadequate skin incision site. Similar to these studies, we demonstrated that lateral perforation occurred most frequently at the concave side of the PT zone in both groups (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). We also demonstrated that the confirmational intraoperative CT enabled re-insertion of the perforated screw, thereby increasing placement accuracy compared with preoperative CT navigation (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). These results highlight the need to pay attention to the area at the concave side of the PT zone when using preoperative or intraoperative CT navigation.\u003c/p\u003e \u003cp\u003eNotably, screw perforation occurred more frequently in the transitional PT/MT or transitional MT/L zone than at the apical vertebra, such as the concave MT, convex MT, concave L, or convex L zones, which involved the greatest degree of rotation (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). On the contrary, Zhang et al. compared intraoperative and preoperative navigation techniques [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e], pointing out that the apical vertebrae were most vulnerable to perforation due to being the most rotated. A possible explanation for this might be that surgeons would be more influenced by the change in trajectory at the transitional versus apical vertebrae [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThis study has some limitations. First, screw misplacement possibly occurred during the correction maneuvers. Even if accurate screw insertion is achieved, correction forces, such as distraction, compression, and rod rotation force, can induce PS perforation in fragile bony cases [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Second, in the intraoperative CT group, we could not detect the exact number of the re-inserted screws because the surgeon decided whether to perform the second 3D scan. Therefore, if the second 3D scan was performed in all cases, a higher accuracy rate would have been noted in the intraoperative group. Despite these limitations, the present study results provide useful information regarding the characteristics of PS perforation using pre- versus intraoperative CT navigation in AIS surgery.\u003c/p\u003e \u003cp\u003eIn conclusion, PS insertion using pre- or intraoperative CT navigation in AIS surgery was accurate, reliable, and safe. The use of O-arm navigation allowed the surgeon to re-insert misplaced screws and increased the placement accuracy rate. The analysis of screw perforation in these cases highlighted the need to pay attention to the concave PT zone in Lenke type 1 or 2 AIS cases.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eFunding:\u003c/h2\u003e \u003cp\u003eThere was no funding source for the work that resulted in the article or the preparation of the article\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eTomohiro Yamada wrote and prepared the manuscript, and all of the authors participated in the study design. All authors have read, reviewed, and approved the article.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eWe would like to thank Editage (www.editage.jp) for English language editing.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eRaw data were generated at Hamamatsu University School of Medicine. Derived data supporting the findings of this study are available from the corresponding author on request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAndrade C (2018) Sedative Hypnotics and the Risk of Falls and Fractures in the Elderly. J Clin Psychiatry, 79(3)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBaldwin KD, Kadiyala M, Talwar D, Sankar WN, Flynn JJM, Anari JB (2022) Does intraoperative CT navigation increase the accuracy of pedicle screw placement in pediatric spinal deformity surgery? A systematic review and meta-analysis. Spine Deform 10(1):19\u0026ndash;29\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBandela JR, Jacob RP, Arreola M, Griglock TM, Bova F, Yang M (2013) Use of CT-based intraoperative spinal navigation: management of radiation exposure to operator, staff, and patients. World Neurosurg 79(2):390\u0026ndash;394\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCui G, Wang Y, Kao TH et al (2012) Application of intraoperative computed tomography with or without navigation system in surgical correction of spinal deformity: a preliminary result of 59 consecutive human cases. Spine (Phila Pa 1976), 37(10):891\u0026ndash;900\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGonschorek O, Hauck S, Spiegl U, Wei\u0026szlig; T, P\u0026auml;tzold R, B\u0026uuml;hren V (2011) O-arm(\u0026reg;)-based spinal navigation and intraoperative 3D-imaging: first experiences. Eur J Trauma Emerg Surg 37(2):99\u0026ndash;108\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGuzek RH, Mitchell SL, Krakow AR, Harshavardhana NS, Sarkissian EJ, Flynn JM (2021) Morphometric analysis of the proximal thoracic pedicles in Lenke II and IV adolescent idiopathic scoliosis: an evaluation of the feasibility for pedicle screw insertion. Spine Deform 9(6):1541\u0026ndash;1548\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHick JM Complications of Pedicle Screw Fixation in Scoliosis Surgery\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eICRP (2017) Diagnostic reference levels in medical imaging. ICRP Publication 135 Ann Icrp 46(1):1\u0026ndash;144\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJiang H, Qiu X, Wang W et al (2012) The position of the aorta changes with altered body position in single right thoracic adolescent idiopathic scoliosis: a magnetic resonance imaging study. Spine 37(17):E1054\u0026ndash;E1061\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJutte PC, Castelein RM (2002) Complications of pedicle screws in lumbar and lumbosacral fusions in 105 consecutive primary operations. Eur Spine J 11(6):594\u0026ndash;598\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKao FC, Huang YJ, Chiu PY, Hsieh MK, Tsai TT (2019) Factors Predicting the Surgical Risk of Osteoporotic Vertebral Compression Fractures. J Clin Med, 8(4)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKotani Y, Abumi K, Ito M et al (2007) Accuracy analysis of pedicle screw placement in posterior scoliosis surgery: comparison between conventional fluoroscopic and computer-assisted technique. Spine (Phila Pa 1976) 32(14):1543\u0026ndash;1550\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLaine T, Schlenzka D, M\u0026auml;kitalo K, Tallroth K, Nolte L-P, Visarius H (1997) Improved accuracy of pedicle screw insertion with computer-assisted surgery: A prospective clinical trial of 30 patients. Spine 22(11):1254\u0026ndash;1258\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLaudato PA, Pierzchala K, Schizas C (2018) Pedicle Screw Insertion Accuracy Using O-Arm, Robotic Guidance, or Freehand Technique: A Comparative Study. Spine (Phila Pa 1976), 43(6):E373-E378\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLenke LG (2005) Lenke classification system of adolescent idiopathic scoliosis: treatment recommendations. Instr Course Lect 54:537\u0026ndash;542\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMAJ Philip J, Belmont J Accuracy of Thoracic Pedicle Screws in Patients with and Without Coronal Plane Spinal Deformities\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eParent S, Labelle H, Skalli W, de Guise J (2004) Thoracic Pedicle Morphometry in Vertebrae from Scoliotic Spines. 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Spine 37(25):E1580\u0026ndash;E1587\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWollowick A, Sugarman E, Nirenstein L, Amaral T, Thornhill B, Sarwahi V (2010) Incidence, Distribution, and Surgical Relevance of Abnormal Pedicles in Normal and Deformed Spines: A CT-Based Study of 6256 Pedicles. Spine J 10(9):S3\u0026ndash;S4\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYamada T, Hasegawa T, Yamato Y et al (2023) Characteristics of pedicle screw misplacement using freehand technique in degenerative scoliosis surgery. Arch Orthop Trauma Surg 143(4):1861\u0026ndash;1867\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang W, Takigawa T, Wu Y, Sugimoto Y, Tanaka M, Ozaki T (2017) Accuracy of pedicle screw insertion in posterior scoliosis surgery: a comparison between intraoperative navigation and preoperative navigation techniques. Eur Spine J 26(6):1756\u0026ndash;1764\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"pedicle screw, computed tomography navigation, adolescent idiopathic scoliosis, proximal thoracic","lastPublishedDoi":"10.21203/rs.3.rs-5452062/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5452062/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003eTo evaluate the accuracy of pedicle screw (PS) and clarify the characteristics of pre- or intraoperative perforation using computed tomography (CT) navigation in adolescent idiopathic scoliosis (AIS) surgery.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eOne hundred and seven patients who underwent surgery were retrospectively selected. Overall, 853 PSs were implanted in 48 patients using preoperative CT, whereas 1,059 PSs were implanted in 59 patients using intraoperative CT with a second intraoperative 3-dimensional (3D) scan. We analyzed the postoperative CT images for pedicle perforation using Rampersaud criteria.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eTotal PS placement accuracy (grade A, B) was significantly higher in the intraoperative group than the preoperative CT group (97.2% vs 94.8%, respectively; \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.008). Accuracy was significantly higher among Lenke type 1 AIS cases in the intraoperative CT group (97.8% vs 95.1%, respectively; \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.014). Grade D perforation occurred most frequently at the concave side of proximal thoracic (PT) zone, followed by the transitional PT/main thoracic zone in both groups. The second intraoperative 3D scan allowed the re-insertion of 10 screws to prevent grade D perforation in the intraoperative CT group.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eBoth navigation systems were sufficiently accurate. However, surgeons must be careful at the concave side of the PT zone. Intraoperative CT navigation yielded higher accuracy by using the intraoperative second 3D scan than preoperative navigation.\u003c/p\u003e","manuscriptTitle":"Concave side of proximal thoracic zone vulnerable to pedicle screw perforation in adolescent idiopathic scoliosis surgery: Comparative analysis of pre- and intraoperative computed tomography navigation","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-12-19 12:54:54","doi":"10.21203/rs.3.rs-5452062/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"971dee05-41c2-4f3b-b40d-2a2b1fd0b00f","owner":[],"postedDate":"December 19th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-12-19T12:55:15+00:00","versionOfRecord":[],"versionCreatedAt":"2024-12-19 12:54:54","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5452062","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5452062","identity":"rs-5452062","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}